Aerial system for use in wireless telegraphy and telephony



y 1933- c. s. FRANKLIN ET AL 1,908,595

AERIAL SYSTEM FOR USE IN WIRELESS TELEGRAPHY AND TELEPHONY Filed Oct.16. 1926 SOURCE 2C9 INVENTORS CHARLES s. FRANKLI ERNEST m ATTORNEYPatented May 9, 1933 UNITED STATES PATENT orrlca CHARLES SAMUELFRANKLIN, or BUGKHURST HILL, AND ERNEST' GREEN, or HENDON,

LONDON, ENGLAND, AssIGnoR s ro RADIO coaroaarlonor AMERICA, A GORBORA-TION OF DELAWARE AERIAL SYSTEM FOR USE IN WIRELESS TELEGRAPHY ANDTELEPHONY Application filed October 16, 1926, Serial No. 142,517, and inGreat Britain October 19, 1925.

This invention relates to aerial systems for use in wireless telegraphyand telephony, and more particularly to aerial systems comprising anumber of aerials arranged in a plane and adapted to radiate moststrongly in a direction at right angles to that plane.

The object is usually to produce by such aerial systems a substantiallyplane current sheet which will radiate a substantially planeelectromagnetic wave.

The directional properties of such an aerial system, as expressed by itspolar curve of radiation, are a known function of its dimensionsrelative to the wave length.

If the aerials comprised in such a system are supplied with currents inphase with one another, and of substantially the same strength, thepilar curve of radiation of the whole system comprises a main beam and anumber of small loops. For example, in the case of an aerial systemcomprising a number of vertical aerials, spaced apart at less than halfa wave length in a plane and fed with equal currents all in phase, thenif the width of the whole aerial system be n wave lengths, thehorizontal polar curve of radiation will have #1 loops on either side ofthe main beam between the direction of maximum radiation and a line atright angles thereto. The maximum intensities of these loops bearconstant ratios to the maximum intensity of the main beam, viz:

beginning with the side loops nearest to said main beam.

According tothis invention an aerial system of the type described isconstructed of a number of coplanar aerials which are spaced apart atequal distances and fed with currents of strength decreasing from thecentre outwards; or the aerials may be spaced apart by distancesincreasing from the centre of the system outwards, and fed with equal Ioutwards, and the strength of the currents decreased from the centreoutwards.

We have found that with such an arrangement the strength of the sideloops of the polar curve of radiation can be greatly di-. minished Inone formof construction an aerial system comprises a number of coplanaraerials equally spaced from one another, at less than half a wavelength, and supplied with currents whose strengths diminish uniformlyfrom the centre aerial tozero at the end aerials. With such aconstruction we have found the number of the loops on either side of themain beam to be reduced to r (where the aerial system is a wave lengthswide) and their maximum intensities to be reduced to e erthat of themain beam.

Ainore complete understanding of the indicate like parts, Figure 1 showsan arrange- 1 ment in which a plurality of aerials, 1 2, 3, 4, 5, 6, 7,and 8, spaced apart equal distances-in a plane, are energized by feeders11', 12, 13, 1 1, 15,16, 17 and 18 respectively. The feeders eachterminate in an inductance coupled,

as shown, to an inductance in the respective aerial on the one hand andin a source of energy 19 on the other hand.

Means is provided between the source and each feeder for progressivelydecreasing the current efi'ective in the several aerials from the centeraerials outwards in both directions. This has been indicated in thedrawings by using heavy lines to show the center pair of aerials and bydecreasing the weight of the lines in the aerials from the center pairof aerials outwards in both directions. The

specific form, whichthe amplitude reducing ,8

means may take, is immaterial and, since it forms no part of the presentinvention, has not been included separately but is included with theshowing of the source. All that is required is that the amplitude ofcurrents fed to aerial 1 is less, as indicated at I, than the amplitudeof the current fed to aerial 2, which is, as indicated at I, in turnless than the current' fed to aerial 3, etc; In a similar manner theamplitude of the current in aerials 5, 6, 7, and 8 decreasesprogressively from 5 to 8.

Figures 2 shows a modification in which the aerials 1 to 8 inclusive arespaced apart unequal distances, the distances between aerials increasingfrom the center of the system outwards in both directions. The aerialsare fed by feeders 11 to 18 inclusive as in Figure 1. In thismodification, however, the amplitude of the currents in all of theaerials is maintained the same. Accordingly the amplitude determiningmeans used with the modification of Figure 1 is unnecessary. The factthat the amplitude of the current in all of the aerials is the same hasbeen denoted by showing all of the aerials with the same weight lines.The current from the source may be fed directly to the different aerialsin phase.

In Figure 3 is shown an aerial system in which is incorporated theenergy concentratsetting up in said aerials currents which diminish instrength from the centre aerial outwards, said aerials being spacedapart by distances increasing from the centre outwards.

2. An aerial system as claimed in claim 1, in which the currentsdiminish uniformly.

3. An aerial system as claimed in claim 1 in which the spacing distancesbetween the aerials increase uniformly,substantially as hereindescribed.

4:. An aerial system comprising a plurality of aerials located in aplane and spaced apart by distances increasing from the center outwardin both directions, and means for energizing said aerials, in phase,whereby said system will radiate'a-sharp beam of energy.

CHARLES SAMUEL FRANKLIN. ERNEST GREEN.

ing features of the modifications shown in and the strength of thecurrents in the aerials 7 decreases as indicated by I, I, 1 etc., and bythe relative thickness of the aerials in the system from aerials 4 and 5outwards in both directions.

It has been found that by providing an aerial system arranged asillustrated hereinbefore, a concentrated center beam of energy will beradiated in a direction normal to a plane through the several aerialswhen the aerials are excited in phase, while radiations in directionsother than that taken by the main beam will be greatly diminished.

Having described our invention what we claim is: v

1. An aerial system of the kind comprising a number of coplanar aerialsfed with currents in phase with one another, means for

